Any self-respecting fan of jazz vocals will already have some version or other of the 1950s duets, but there are probably an awful lot of newcomers, seduced by Diana Krall or Norah Jones, for whom this is new territory. If you want relaxed, off-the-cuff Gershwin and Berlin, this is about as good as it gets: Fitzgerald and Armstrong swapping genial choruses in front of a purring rhythm section led by Oscar Peterson. The orchestral covers from Porgy and Bess are slightly less inspired, but have their moments. Smooth jazz has, rightly, become a dirty word of late; once upon a time, it used to mean something. Four star